Abstract
In this study, the author proposes a method to compensate the deviation of B and C for the marine magnetic compass of fishing vessels by using the deviation table and leading lines. The advantage of this proposed method is to compensate the marine magnetic compass in two directions instead of four ones as in the traditional ERY method. Besides, this proposed method considers the leading lines to adjust the deviations for fishing vessels which are not equipped with gyro compass. This study can be seen as a developing step to improve the traditional ERY method for adjusting the deviation of the marine magnetic compass.